The present invention relates to a system and method that estimates the location of a single or multiple transmitters. More particularly, the present invention relates to such an estimation method that uses measured data such as Received Signal Strength Indication (RSSI) data collected by a scanning and tracking receiver such as that which may be commercially available.
The non-invasive estimation of transmitter location and configuration based on signals received from such transmitter(s) is considered to be highly useful in many circumstances. For example, an investment banker or the like may employ such information for preliminary asset determination among other things; a tower company or the like may employ such information for development of a business plan and guidance for site acquisition personnel among other things; a competitor wireless service provider or the like may employ such information to assess the overall system layout of other service providers in a particular market among other things; and a consultant or the like may employ such information to provide value added services to improve overall system performance to a client among other things.
One typical methodology that may be employed to non-invasively estimate the location of a particular transmitter is to measure signal strengths of signals received from such transmitter at several reception locations, to estimate distance based on such measured signal strengths, and then to triangulate based on such estimated distances. However, and importantly, many factors affect signal strength as measured at a particular reception location, including but not limited to transmission power, terrain, atmospheric conditions, interference, line of sight issues, etc. Thus, the distances estimated from such measured signal strengths have relatively large margins of error, and accordingly triangulation calculations based on such estimated distances have relatively large margins of error, too. Ultimately, the margin of error of such triangulation calculations is so significant as to render the result of the calculations highly suspect if not meaningless.
Accordingly, a need exists for a system and methodology for non-invasively estimating transmitter location and configuration information, whereby the margin of error of the result of the methodology is within a more acceptable range.
The present invention satisfies the aforementioned need by providing a method for estimating the location of a transmitter based on signals transmitted therefrom. The transmitted signals are received at a plurality of reception locations and are employed to compile data including a plurality of entries, where each entry includes a received signal level (RSL) of a received signal, a channel identification of the received signal, and position information corresponding to the respective reception location when the received signal was received.
In the method, the entries are organized into groups according to channel identification, and, in each group, entries having the same position information are consolidated. Thereafter, for each entry, the distance DRT between the reception location and the transmitter is estimated, and the distance DRR between the reception location thereof and an adjacent reception location is also estimated. Then, for each group, the location of the transmitter corresponding to the channel identification of such group is estimated based on the distances DRT and DRR.